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678 GLADSTONE AND TRIBE’S RESEARCHES ON THE Published on 01 January 1873. Downloaded by Christian Albrechts Universitat zu Kiel 23/10/2014 03:48:39.

XX’C7rII.-Researches on the Action of the copper-zinc Couple on Oryank Bodies. Part 11. On the Iodides of Amy1 and Methyl. By J. H. GLADSTONE,PhD.,F.R.S., and ALFREDTRIBE, F.C.S.

FRANKLANDfound that “ iodide of amyl is acted upon by zinc with much more difficulty than the corresponding ethyl compound ;”* he speaks of the necessity of “ a very nice management of the tempera- * Chem. SOC. J., iii, 31. View Article Online

ACTION OF THE COPPER-ZINC COUPLE ON ORGANIC BODIES. 679

ture," and though he mentions zinc-amyl among the results of the reaction, he never obtained it in any quantity by this method. For the decomposition of iodide of amyl he resorted to the use of zinc-amalgam in powder in sealed tubes at a temperature a little above that of the boiling-point of the . He thus obtained, not zinc-amyl but a mixture of three hydrocarbons, viz., amyl, CloH,,, a light liquid boiling at 155" ; hydride of amyl, C5H12,an exceedingly mobile liquid with an agreeable odour, boiling at 30" ; amylene, C,H,,, another limpid liquid boiling at 35", and combining with fuming sulphuric acid. It appeared to us therefore a point of special interest to ascertain whether our copper-zinc couple was capable of effecting the decompo- sition of amyl iodide with production of an organo-metallic body. On performing the experiment in a manner analogous to that described in our previous communication on iodide of ethyl, we at once perceived that it was a question of temperature. At 100" there is no appreciable action, but upon heating the flask somewhat higher in a paraffin bath, decomposition ensues. It however, proceeds slowly, unless the temperature be raised to near the boiling-point of the iodide (146") ; but at such a temperature 5 C.C. of am$ iodide are completely converted in about a quarter of an hour. Volatile bodies are formed which, if allowed to distil over into a receiver, are found to have the properties of amyl hydride and amylene described above, while in the flask there remain another limpid liquid and a white crystalline body, which appears to be but sparingly soluble in it. If the flask be nor heated a little higher, this liquid distils over, and on examination proves to consist almost wholly of one substance, having the properties of Frankland's amyl. At about the temperature necessary to distil off the amyl, there begins to form a body which fumes in the air ; and at 160", or above, the white crystals suffer decomposition, with production of a liquid that distils over, and Published on 01 January 1873. Downloaded by Christian Albrechts Universitat zu Kiel 23/10/2014 03:48:39. leaves a solid substance in the flask. The liquid is again almost pure amyl. As both stages of this reaction have yielded am$, this would appear to be a productive method of preparing that substance. It was evidently worthless, however, for the preparation of zinc-amyl, unless it could be modified in some favourable direction. Such a modification was not far to seek. If during the formation of the crystalline body, the volatile hydrocarbons are caused to fall back again into the flask, and then the contents are rapidly distilled off either over a flame or by a bath at 160" or higher, a good deal of zinc-amyl is carried over with the other , and collects with them in the receiver. The following are the quantitative experiments that were performed, arranged according to the temperature at which the first operation was condncted. As in the case of +theethyl iodide 5 C.C. were always 3~2 View Article Online

680 GLADSTONE AND TRIBE'S RESEARCHES ON THE employed, and the amount of zinc compound distilled was estimated by shaking the contents of the receiver with water, and weighing the oxide produced.

Experi- Temperature Amount Zinc -amyl of ZnO ment. Of bath* Dur:p heating. decomposition. obtained. indicated.

~ ~- -- A...... 100" none none - grm. B ...... 12'7O--13lo about 2 C.C. 0 *095grm. '244 ), c ...... 127"-130° -complete 0.324 ,, '834 ,, I)...... 138"-142" ,Y 0.222 ,) 571 ,, E...... l4oo-160 * 7) 0.150 ,, m6 P...... 145" 4.25 C.C. 0.320 ,, -824 ), G..*. *. 145" complete 0 *444 ,) 1*1&3 ,, H...... 145" 77 0.406 ,, 1*045 ,, 177"-188" none -I ...... 1, As the amount of zinc-amyl theoretically attainable from 5 C.C. of the iodide is 3.9'7, the best of the above experiments gave only *28per cent. of what might have been hoped for. It then occurred to us that if the zinc-amyl, which is said to boil at ZZO", could be raised in vapour at or near the temperature at which the crystalline body splits up, that is about 150", it might be procured in larger quantity. The first part of the operation was therefore per- formed as before, namely, by heating the flask in a paraffin bath at 145" for 15 or 18 minutes, but a pump was attached to the distilling apparatus, and a good vacuum was made. The flask was then heated, and the vapour was pumped into water. The results were :-

I Experiment. 1 Second heating. ZnO obtained. Zinc-amyl indicated. '- '- -____.-- Published on 01 January 1873. Downloaded by Christian Albrechts Universitat zu Kiel 23/10/2014 03:48:39. J ...... I BY gas flame...... 0 *621 1*59 I( ...... 1 By paraffin bath .... 0 *678 1'73

This shows a much larger yield of the zinc-amyl, in fact 40 and $3.5 per cent. of the theoretical quantity. Of course in the receiver it is mixed with the hydrocarbons, espe- cially the less volatile amyl. By careful heating, the great bulk of that liquid may be separated by ; but as we operated on small quantities and the zinc-compound is easily decomposed, we never obtained it in the pure state; still, it answered sufficiently to the description given by Frankland of the zinc-amyl he prepared by the action of mercuric-amyl on zinc, to leave no doubt that it was the same substance. Frankland has pointed out the perfect analogy of the decomposi- View Article Online

ACTION OF THE COPPER-ZINC COUPLE ON ORGANIC BODIES. 681

tion of amyl iodide into the liquid C1,H,,, C5H1,, and C5H10) with the secondary reactions by which ethyl iodide yields the gaseous C~HIO, C2H6and C2H*. But working as he was obliged to do, with zinc- amalgam at a temperature above the boiling-point of amyl-iodide, he obtained little else than the secondary action which we find to accom- pany the formation of amyl-iodide of zinc through the agency of the couple at a lower temperature. We may extend the analogy, for just as the crystalline C,H,I.Zn forms in the one case, so does the crystal- line C,HI,I.Zn form in the other ; two molecules of the one split up by heat into C4Hl0Znand Zn12, and two molecules of the other into CloH2,Znand ZnI,, while in each instance this splitting up is accom- panied by a similar secondary reaction. In the case of the ethyl compound, however, this secondary reaction appears to be princi- pally- 2C2H51Zn= ZnI, + Zn + C,H, + C2H4. while in the case of the higher carbon molecule, it is mainly-

2C5H,,IZn = ZnI, + Zn + CI0H2,.

Acti0.n om Amy1 Iodide and Vater or Alcohol. As zinc alone is capable of decomposing a mixture of arnyl iodide and water at 140" with production of arnyl hydride, it was interesting to ascertain whether our couple would do the same at a lower tempera- ture. The experiment was conducted as in the case of the ethyl-compound by pouring 5 C.C. of the iodide on to a couple washed withwater but not dried. Action was found to take place slowly at the temperature of the labo- ratory lo", but in a water-bath at 100" it proceeded so rapidly that it appeared complete in an hour and a-half. The vapours produced Published on 01 January 1873. Downloaded by Christian Albrechts Universitat zu Kiel 23/10/2014 03:48:39. were made to pass up a tube about 16 inches long, which condensed any volatilised water or iodide, and then through a Liebig's into an iced receiver. A liquid was thus collected which was lighter than water, not miscible with it, and boiled when the vessel containing it was immersed in a bath at 339a in its vapour registering 29". Any further proof that this was the same hydrocarbon as Frankland obtained at a higher temperature, seemed unnecessary. The residue in the flask resembled that from the ethyl compound treated in the same manner. We repeated this experiment, using absolute alcohol instead of water, and found as before that the action proceeded slowly at lo", but at 70" it seemed to be complete in three-quarters of an hour. The same volatile hydrocarbon was produced, and the residue in the flask gave the properties of the iodo-ethylate of zinc described in our former View Article Online

682 GLADSTONE AND TRIBE'S RESEARCHES, ETG. paper as occurring when ethyl iodide and alcohol react in presence of the couple. This circumstance, and the fact that no permanent gas is given off during the experiment with the amyl compound, show that it is the radical of the iodide, ,and not that of the alcohol, which is hydro- genised. This reaction offers a ready method of preparing pure amyl hydride.

Actiort 0% Methyl Iodide artd Fai?er or Abohol. Methyl iodide was found to be decomposed very slowly by a dry copper-zinc couple, even at the boiling-point of the liquid. If, however, the couple be wet with water, decomposition proceeds even at the ordinary temperature. An experiment made as usual with 5 C.C. of the iodide at 12", the flask being shaken from time to time, evolved permanent gas during 18 hours, at the end of which time 1414 C.C. had been evolved. This gas, after beiag washed, burned with a blue scarcely luminous flame. It was passed through bulbs containing alcohol to remove any vapour of the iodide, and afterwards through water, and analysed by Bunsen's method. There was no absorption by fuming sulphuric acid. After removal to the , the following data were obtained :

------pressure. Gas used (moist) ...... 35 -944 10 -2 451 745 "72 10 '02'7 After addition of air and 0) (moist) ...... 246 .369 10.3 249.5 '751 -56 117.210 After combustion (moist). . . . 21'7.2'7 9.0 2'77'9 750 -3 9'7,339 After absorption of CO, (dry) 198 *86 11 -0 297 -1 '752 '31 87 *238 Published on 01 January 1873. Downloaded by Christian Albrechts Universitat zu Kiel 23/10/2014 03:48:39.

~~ ~ which gave the following numbers as compared with those calculated for methyl hydride :- Found. Calculated. Gas burnt . . . . ,. 10.03 - Contraction .. . . 19.87 20.06 Carbonic acid . . 10.10 10.03 The amount of this gas which might have been evolved, according to theory, from 5 C.C. of methyl iodide is 1782 C.C. The residue in the flask was similar to that in the corresponding reaction with iodide of ethyl and water. The nature of the reaction is evidently the same, and may be thus expressed- CH,I + H,O + en = CH, + zn{ ko* View Article Online

ARMSTRONG ON THE ACTION OF THE ACID CHLORIDES. 683

When 10 C.C. of absolute alcohol were added to 3 C.C. of methyl iodide, and the mixture was submitted to the action of the couple at lo", it was about 20 minutes before evolution of gas commenced, but then the temperature inside the flask rose, and the action proceeded so rapidly that in half an hour 500 C.B. were obtained. The total col- lected was 897 C.C. In another experiment, where the iodide was poured on to a couple wet with alcohol, and the flask was immersed in water at 12", the gas amounted to 1063 C.C. It burnt with a blue scarcely luminous flame. The residue in the flask gave the reaction of the iodo-ethylate of zinc, as in the analogous experiments with ethyl and amyl-compounds. Either of the reactions just described offers a simple method for pre- paring pure methyl hydride, or marsh-gas. Published on 01 January 1873. Downloaded by Christian Albrechts Universitat zu Kiel 23/10/2014 03:48:39.